function vnew=vcycle1(vold,f,nu1,nu2)
% VCYCLE1 V-cycle with a direct solve at the coarsest level.
global sigma 
lmin=3;
nt=length(f); l=log2(nt-1);
if l==lmin
	vnew=helmholtz(f);
else
        vnew=vold;
	for ij=1:nu1
		vnew=dampj(vnew,f);
	end
	nt=length(vnew); nl=nt-1; h=1/nl; hm2=nl*nl;
	av=zeros(nt,1);
	av(2:nt-1)=-vnew(1:nt-2)+(2+sigma*h*h)*vnew(2:nt-1)-vnew(3:nt);
	r=f-hm2*av;
	fc=ftoc(r); nc=length(fc); vc=zeros(nc,1);
	vc=vcycle1(vc,fc,nu1,nu2);
	vnew=vnew+ctof(vc);
	for ij=1:nu2
		vnew=dampj(vnew,f);
	end
end